Method, system, and program product for eliminating error contribution from production switchers with internal DVEs

ABSTRACT

Measurement of the relative timing between images and associated information, for example video and audio. Image mutual event characteristics are recognized in the images and associated mutual event characteristics are recognized in the associated information. The image mutual events and associated mutual events are compared to determine their occurrences, one relative to the other as a measure of relative timing. Particular operation with audio and video signals is described.

BACKGROUND OF INVENTION

1. Field of the Invention

The invention relates to the creation, manipulation, transmission,storage, and especially synchronization of multi-media entertainment,educational and other programming having at least video and associatedinformation. The invention will find particular use with respect to thecreation and distribution of television programs.

2. Background Art

The creation, manipulation, transmission, storage, etc. of multi-mediacontent, be it entertainment, educational, scientific, business, andother programming having at least video and associated informationrequires synchronization. Typical examples of such programming aretelevision and movie programs, motion medical images, and variousengineering and scientific content. These are collectively referred toas “programs.”

Often these programs include a visual or video portion, an audible oraudio portion, and may also include one or more various data typeportions. Typical data type portions include closed captioning,narrative descriptions for the blind, additional program informationdata such as web sites and further information directives and variousmetadata included in compressed (such as for example MPEG and JPEG)systems.

Often the video and associated signal programs are produced, operatedon, stored or conveyed in a manner such that the synchronization ofvarious ones of the aforementioned audio, video and/or data is affected.For example the synchronization of audio and video, commonly known aslip sync, may be askew when the program is produced. If the program isproduced with correct lip sync, that timing may be upset by subsequentoperations, for example such as processing, storing or transmission ofthe program.

One aspect of multi-media programming is maintaining audio and videosynchronization in audio-visual presentations, such as televisionprograms, for example to prevent annoyances to the viewers, tofacilitate further operations with the program or to facilitate analysisof the program.

The video and audio signals in a television system are increasinglybeing subjected to more and more steps of digital processing. Each stephas the potential to add a different amount of delay to the video andaudio, thereby introducing a lip sync error. Incorrect lip sync is amajor concern to newscasters, advertisers, politicians and others whoare trying to convey a sense of trust, accuracy and sincerity to theiraudience. Studies have demonstrated that when lip sync errors arepresent, viewers perceive a message as less interesting, moreunpleasant, less influential and less successful than the same messagewith proper lip sync.

Because light travels faster than sound, we are used to seeing eventsbefore we hear them—lightning before thunder, a puff of smoke before acannon shot and so on. Therefore, to some extent, we can tolerate “late”audio. Unfortunately, as shown in FIG. 1, even in a simple televisionsystem, the video is almost always delayed more than the audio, creatingthe unnatural situation of “early” audio. Any one contributor to the lipsync error may or may not be noticeable. But the cumulative error fromthe original acquisition point to the viewer can easily become bothnoticeable and objectionable. The potential for lip sync errorsincreases even further when MPEG compressed links are added to one ormore stages of the overall system.

As shown in a typical television FIG. 1, as video moves from videopickup devices, typically CCD cameras, 101 and 111, to framesynchronizers, 103, production switchers, 121, digital video effects,121 and 131, noise reducers and intermediate transmitters, 135, andreceivers, 141, including MPEG encoders and decoders, more framesyncronizers 143, local transmitters, 151, tuners and demodulators, 161,and TVs with digital processing, 171 and the like, and as the audio goesfrom remote and studio pickup, 101 and 111, to an audio board, 123,further audio processing, 133, intermediate transmitters, 135, andreceivers, 141, through audio limiters, 145, and local transmitters,151, to a tuner-demodulator, 161 and an audio amplifier and speaker,173, the video is delayed more than the audio. The cumulative delay ofthe video with respect to the audio can be 6 or more frames. With theinclusion of video and audio compression in any part(s) of the systemthe video delays with respect to audio can be much more. Worse yet, theamount of video delay frequently jumps by a frame or more as theoperating mode changes, or as frames of video are dropped or repeated toachieve synchronization of the video to studio and other references.Using a fixed audio delay to “mop up” the audio to video timing errorsis rarely a satisfactory solution because of the constantly changingvideo delay.

While not shown in this typical system of FIG. 1, data is frequentlycarried along with the video signals through much of the system, viaseparate paths, thus when the video is delayed as described above, thetiming of the data relative to the video is disrupted. Using a fixeddata delay to “mop up” the data to video timing errors is rarely asatisfactory solution because of the constantly changing video delay

Standards committees in various countries have studied the lip syncproblem and have set guidelines for the maximum allowable errors. Forthe most part, these studies have determined that lip sync errors becomenoticeable to most viewers if the audio is early by more than 25-35milliseconds (about 1 NTSC frame) or late by more than 80-90milliseconds (2.5-3.0 NTSC frames). In June of 2003, the AdvancedTelevision Systems Committee (ATSC) issued a finding that stated “ . . .at the inputs to the DTV encoding device . . . the sound program shouldnever lead the video program by more than 15 milliseconds, and shouldnever lag the video program by more than 45 milliseconds.” The findingcontinued “Pending [a finding on tolerances for system design],designers should strive for zero differential offset throughout thesystem.” In other words, it is important to eliminate or minimize theerrors at each stage where they occur, instead of allowing them toaccumulate.

Fortunately, the “worst case” condition in FIG. 1 is now less likely topresent itself than was the case a few years ago. Firstly, it is nowquite common to install audio tracking delays, exemplified by the PixelInstruments AD-3000 or AD-3100, alongside each video frame synchronizeror other video delay devices having delay signal outputs, therebyeliminating at least one common source of variable lip sync errors. TheAD-3000 and AD-3100 variable audio delays are available from PixelInstruments Corp. of Los Gatos, Calif.

Secondly, due to the continuing cost effectiveness of digitalelectronics, newer master control switchers have an internal DVE forsqueezeback operation rather than an external DVE. This allows the useof a constant insertion delay of 1 frame for both the video and theaudio paths in all modes of operation.

Unfortunately, again due to the continuing cost effectiveness of digitalelectronics, newer master control switchers are now incorporating builtin video frame synchronizers, scan converters and other video delayingcircuitry.

Since the 1970s, digital video effects processors (DVEs or transformengines) have been used to produce “over the shoulder”, “double box” andother multiple source composited effects. The video being transformed isdelayed (usually by one or more frames) relative to the background videoin the switcher. So, any time one or more DVE processors are on-air, theassociated video sources will be delayed, resulting in a lip sync error.In the past, when the DVE processor was external to the switcher, atally signal from the switcher could be used to trigger the insertion ofa compensating audio delay when the DVE in on-air. However, today'sproduction switchers are usually equipped with internal DVEs and a tallyoutput is no longer available.

Thus, a need exists for a method, system, and program product forproducing time synchronized multi-media signals.

SUMMARY OF THE INVENTION

The present invention provides for method of producing time synchronizedmulti-media signals.

The preferred embodiment of the present invention is a method, apparatus(system), and program product where audio and video portions ofmulti-media content, e.g., a television or other program, may besynchronized by inserting and controlling appropriate audio delays. Thisincreases the apparent synchrony of the desired signals.

The method, system, and program product described herein provide forentering a delay value in the relative timing of a video signalconveying a plurality of images and an associated signal, as an audiosignal. This is accomplished by a method, system and program product forproducing time synchronized multi-media signals. This is done byinputting a start pulse, for example, a GPI Start pulse, a stop pulse,for example, a GPI Stop pulse, and a tally line for each video input.The next step is generating a Timer On/Off signal and a Time Valuesignal for each set of start pulses, stop pulse and tallies, andproviding the Timer On/Off signal and a Time Value signals to a router.These outputs are properly associated with each other, processed andcoupled to an audio synchronizer as one or more control signals, whichin the preferred embodiment are a single signal of delay steering pulsesfor control of the delay of the audio signal.

One feature of the present invention is that the number of Interfacesand Tally contact closures can be stored in the timelines to controlexternal devices. In other words, by use of the router, variouscombinations of input signals (tallies & GPIs) can be associated withthe delay setting to create delay output signals. Since the video delaythrough the switcher is usually predictable (based on the combination ofeffects), an external interface can be used to interpret the GPI andtally outputs and generate the necessary steering commands to controlaudio synchronizers. This permits automatic correction of the lip syncerrors. For example, the DG-1200 interface from Pixel Instruments can bepreset to provide up to twelve different delays and can steer up to fiveaudio synchronizers.

Depending on the application, the insertion of the audio delay can betriggered by tally signals, GPIs, or a combination of both. Gating thetally signal with GPIs improves the immunity to false delay insertion.

For example, by way of illustration of the capabilities of the preferredembodiment of the invention, consider a simple video switcher systemhaving two DVEs. The first DVE has a variable delay of 0-1.5 frames andthe second DVE has a fixed delay of 2.25 frames. DVE 1 has acorresponding pair of GPI signals and a tally signal. DVE 2 has only anassociated tally signal. For DVE 1 the GPI signals will indicate thecurrent delay, that is the GPI start is triggered when a particularvideo frame enters DVE 1 and the GPI stop is triggered when that sameparticular video frame exits DVE1. The associated tally is asserted whenthe output of DVE1 is being utilized by the switcher. When the output ofDVE 2 is being utilized by the switcher its associated tally isasserted. The DG-1200 will (as set up by an operator) receive the twotallys and two GPI signals as well as a 2.25 frame delay value. Thesesignals and the delay value are utilized to create a delay output signal(DDO pulse) to control an audio synchronizer to cause the audiosynchronizer delay to match the video delay of the production switcheras the two DVEs are inserted into (and taken out of) the video path. Thetwo GPIs corresponding to DVE 1 are utilized to determine the currentDVE 1 delay. The two tallies are used to determine if one or both DVEsare inserted into the video path. If DVE 1 is inserted (as determined byits corresponding tally), its delay (as determined by the GPIs) is addedto the DDO signal. If. DVE 2 is inserted (as determined by itscorresponding tally) the 2.25 frame delay value is inserted into the DDOsignal. Consequently the DDO may indicate 0 delay (neither DVE is used),the DVE 1 delay (DVE 1 is in use), a 2.25 freme delay (DVE 2 is in use)or a delay of 2.25 frames plus the DVE 1 delay (both DVEs are in use).

The preferred embodiment of the invention has the ability to utilize andconfigure its various inputs to match differing video systems. As justone of many possible examples, the GPIs may be utilized as an indicatorof when a DVE is being used (as compared to indicating a varying delayas in the above example), or as an additional indicator along with thetally.

THE FIGURES

FIG. 1 illustrates a typical train of prior art processes and units togo from a multi-media pickup, through pre-transmission level processing,transmission, receiving, and receiver level processing (including tuningand demodulation) to final presentation to an end user or viewer.

FIG. 2 shows a system for using General Program Interfaces and Tallies,through a control router, to timers, to generate delay steering pulsesto an audio synchronizer.

FIG. 3 illustrates a system for receiving video inputs through a videoswitcher with internal DVE's to generate GPI's and Tally signals, to aninterface with a plurality of audio delays which system includes anembodiment of the present invention operable to generate delay steeringpulses to an audio mixer, where the audio mixer provides a correctedaudio output. Note that while FIG. 3 illustrates a typical system by wayof example, one of ordinary skill will recognize that the teachingsherein are applicable to general systems, methods and products whereinvideo signal processing causes changing video delays.

FIG. 4 illustrates video inputs and audio inputs with a video switcherwith internal DVE's to generate GPI's and Tally signals, which systemincludes an embodiment of the present invention operable to generate adelay steering pulse to control a single audio delay operating on audioout of an audio mixer to provide a corrected audio output. Note thatwhile FIG. 4 illustrates another typical system by way of example, oneof ordinary skill will recognize that the teachings herein areapplicable to general systems, methods and products wherein video signalprocessing causes changing video delays.

FIG. 5 illustrates a schematic diagram of the preferred embodiment ofthe present invention having an interface to interpret the GPI and tallyoutputs and generate the necessary steering commands (preferred to beDDO signals) to control one or more audio synchronizers to permitautomatic correction of timing and synchronization errors, such as lipsync errors.

DETAILED DESCRIPTION OF THE INVENTION

The preferred embodiment of the invention produces time synchronizedmulti-media signals. This is done as one example by inputting a startpulse, for example, a GPI Start pulse, a stop pulse, for example, a GPIStop pulse, and a tally line for each video input. The next step is forexample generating a Timer On/Off signal and/or a Time Value signal foreach set of start pulses, stop pulse and/or tallies, and providing theTimer On/Off signal and a Time Value signals to a router. Theinformation conveyed by these signals are routed to an audiosynchronizer as delay steering pulses for the audio signal.

The number of GPI and Tally assertions (typically contact closures) canbe stored in these timelines to indicate system configuration and/orcontrol external devices. Since the video delay through the switcher (orother system) is usually predictable (based on the combination ofeffects), an external interface of the present invention can be used tointerpret these GPI and tally outputs and generate the necessarysteering commands to control audio synchronizers. This permits automaticcorrection of the lip sync errors. An interface, such as the DG-1200interface from Pixel Instruments can be preset to provide up to twelvedifferent delays control signals (DDOs) and can steer up to five audiosynchronizers. Depending on the application, the control of the audiodelay can be triggered by tally signals, GPIs, or a combination of both.By utilizing the Control Router 531 which recognizes and couples desiredones of GPI and Tally input signals (for example via 511 and 521), DelayTime Values (for example 513 and 523) to the desired timer(s) (forexample 541 and 551) one or more Delay Steering Signal may be generatedto respond to the video system and reflect the current video delay ofthat system. Gating the tally signal with GPIs can be utilized toimprove the immunity to false delay insertion. Multiple signals may beutilized in sequence or in tandem to improve reliability or to allowoperation with simple or complex video systems.

FIG. 2 illustrates by way of example one preferred embodiment systemwhere GPI start signals, Tally signals, and GPI stop signals are inputto tally latches 211-221. The outputs of the Tally Latches, a timeron/off signals and time values, are input to a control router 231.Additionally, Delay Time values 213-223 are input to the control router.The control router 231 outputs desired ones of the On/Off and Timesignals to individual timers 241-251, which in turn generate delaysteering pulses which are suitably coupled to one or more audiosynchronizers. The Tally Latch may be configured to respond to the inputGPI Start, GPI Stop and Tally signals in various ways. It is preferredthat the outputs of the Tally Latch may be configured (by operator ormanufacture) to represent all of the possible Boolean and/or digitallogic operations of the three input signals, however lesser numbers ofthe possible Boolean and/or digital logic operations may be utilized asdesired. Of particular interest are two combinations of digital logicand Boolean operation which will be described below.

The first combination of particular interest provides selectableinversion of each input, a selection of edge trigger or level triggerfor the GPI inputs to control a set/reset flip flop function. The outputof the set/reset function is anded by the tally signal and the outputselectably inverted. This capability allows any input and outputpolarity. A delay time is established by setting the set/reset functionwith the GPI start (by edge or level trigger) and resetting with the GPIstop (by edge or level trigger). The resulting time duration (pulse) iscounted to provide the established delay time which is coupled to theControl Router. In addition the set/reset pulse from the set/resetfunction itself is anded with the tally and the output coupled (ineither polarity) to the Control Router. The Tally is coupled to theControl Router. In this fashion the inputs to the Control Router are 1)the Tally, 2) a pulse corresponding to the delay between GPI start andstop, 3) that pulse anded by the Tally. In addition a seperate DelayTime Value established by manufacture or the operator is input to theControl Router. The Control Router may then couple various desired onesof its inputs to the desired timer to generate Delay Steering Signals(DDO Pulses). This combination is useful to measure a changing delay asprovided by the timing of the GPI start and stop and the Tally is usedto indicate when that changing delay is inserted in the video signalpath. The changing delay can also be associated with the Delay TimeValue from 213-223, for example added to it. This is useful for systemswhich have a fixed minimum delay to which a variable delay is added.

A second combination of interest provides a selection of edge trigger orlevel trigger for the GPI inputs to control a set/reset flip flopfunction. The output of the set/reset function is anded by the tallysignal and the output selectably inverted. This capability allows anyinput and output polarity. The set/reset level from the set/resetfunction is anded with the tally and the output coupled (in eitherpolarity) to the Control Router. In addition a seperate Delay Time Valueestablished by manufacture or the operator is input to the ControlRouter. The Control Router may then couple various desired ones of itsinputs to the desired timer to generate Delay Steering Signals (DDOPulses). This combination is useful for systems where GPI start and stopare used in addition to the Tally to indicate when a fixed delay isinserted in the video signal path.

The preferred embodiment ability to configure the Tally Latch, as wellas the Control Router and Timers at taught herein is easily provided byconfigurable or programmable logic ICs, such as those manufactured byAltera and xilinx, and operating under control of a suitablemicroprocessor, as is well known to those of ordinary skill in the art.

The aforementioned preferred embodiment of the second combination isavailable commercially in the previously mentioned DG-1200 which wasintroduced at the 2004 National Association of Broadcasters conventionheld Apr. 17-22, 2004 in Las Vegas, Nev. The DG-1200 is available fromPixel Instruments Corporation of Los Gatos, Calif.

As shown in FIG. 2 each of the twelve input channels consists of a GPIStart pulse, a GPI Stop pulse, 211 and 221, and a Tally line, 213 and223. Each input channel also has a linked delay time register with auser selectable value from 20 μsec (nominally zero delay) up to 6.5seconds, in increments of 100 μsec. Delay times can be entered anddisplayed in milliseconds or in TV fields (NTSC or PAL). Otherconfigurations and values may be utilized as desired.

Any input channel and its time value (from either or both the Delay TimeValue and the GPI determined delay time value) can be routed through acontrol router 231 to any of the output timers 241 and 251 and eachtimer can steer a separate audio synchronizer, as an AD-3100 AudioSynchronizer. The output timers, 241 and 251, can have different timevalues and can be turned on and off independently in response to therespective input signals. Also, any timer can be controlled by more thanone input channel. Assume that one switcher effect needs a one frameaudio delay and another effect needs a two frame audio delay. Input #1(or any other input) can enable a 1 frame delay in Timer #3 (or anyother timer) and the associated audio synchronizer, as an AD-3100. Anyother input can be used to enable a 2 frame delay in the same timer.

Pre-Delayed Audio Application

The most comprehensive solution is to add an audio synchronizer, as anAD-3100 Audio Synchronizers, ahead of the audio mixer 315 as shown inFIG. 3. This configuration of a video switcher with internal DVE's 301generating GPI and tally signals, with the GPI and Tally signals asinput to an interface 303 thereby generating delay steering pulses toaudio delays 311 and 313, and the audio mixer 315. This provides acorrected audio output. This ensures that all sources contributing tothe program output have the correct lip sync.

For applications that require more than 5 audio inputs to be delayed,this solution is scaleable with additional DG-1200s and AD-3100s.

Post-Delayed Audio Application

A simpler, but less comprehensive solution is shown in FIG. 4, where asingle audio synchronizer, as an AD-3100 Audio Synchronizer is added atthe output of the Audio Mixer. The amount of delay added to the audiopath is chosen as a compromise for the various sources contributing tothe program output in any given effect.

As shown in FIG. 4video inputs are input to a video switcher withinternal DVE's 411. This provides GPI and Tally signals output as inputto an interface 421, which produces the audio delay steering pulses. Thevideo switcher 411 also produces program video out with video throughDVE paths delayed when a DVE is on the air. The output of the interface421 is input to an audio delay 431, where, along with audio inputs 441through an audio mixer 443 the delay steering pulse correction isapplied to yield a corrected audio output 453.

For example, in a typical newscast over the shoulder shot, the studioanchor has zero video delay and the remote reporter (in the box) has oneframe of video delay. Setting the audio synchronizer, for example, anAD-3100 Audio Synchronizer, delay to between 0 and 0.5 frame is the bestcompromise for both sources. The studio anchor's audio will be slightlylate and the remote reporter's audio slightly early. The residual lipsync errors are reduced compared to doing nothing at all.

Rapid Delay Change With Pitch Correction

Since the video delay of the DVE may be switched in and out of theprogram path several times in a relatively short period, it is essentialthat the audio delay “catch up” quickly.

Conventional audio synchronizers typically change their delay at a rateof 0.5% or less.

This means that for each 1 frame increase or decrease in the videodelay, the audio does not “catch up” for 10 seconds or more. In systemswhere the video delay changes at the start of a 15 second commercial,this would cause most or all of the commercial to suffer lip syncerrors.

In a preferred exemplification, the audio synchronizer, as an AD-3100,incorporates automatic pitch correction to allow rapid delay change (upto 25%) without introducing undesirable artifacts such as pitch shifts,clicks and pops in the output. So, in our example of a one frame changein the video delay, the audio synchronizer will “catch up” in just a fewframes. This is well before the viewer will notice.

The combination of a programmable tally/GPI interface and a fasttracking audio synchronizer provides a flexible cost effective solutionto the lip sync errors introduced by production switchers and digitaleffects processors. It is also applicable to systems that use a mastercontrol switcher with external effects for squeezeback operation.

FIG. 5 illustrates a schematic diagram of an interface to interpret theGPI and tally outputs and generate the necessary steering commands tocontrol audio synchronizers to permit automatic correction of timing andsynchronization errors, such as lip sync errors.

The system shown in FIG. 5 GPI start signals, Tally signals, and GPIstop signals are input to tally latches 511 and 521. The outputs of thetally latches 511 and 521, and delay time inputs 513 and 523, are timeron/off signals and time values. These are inputs to a control router531. The control router 531 outputs On/Off and Time signals toindividual timers 541 and 551, which in turn generate delay steeringpulses to audio synchronizers, not shown.

As shown in FIG. 5 each of the twelve input channels consists of a GPIStart pulse, a GPI. Stop pulse, 511 and 521, and a Tally line, 513 and523. The tally latches 511 and 521 are typically octal transparent, 3state output latches, such as a 74573 series latches with a common latchenable control, a common 3 state output enable control, 3 state outputs.The latch inputs can be set to operate with Tally only, GPI Start andStop Triggers only, Tally gated by GPI Start and GPI Stop, as well asdelay measure which may be provided by a 7474 flip flop, and/or a 74163counter which are responsive to the GPI signals. It is preferred howeverthat these functions be implemented with programmable logic configuredin response to and operating in conjunction with a microprocessor.

Each input channel also has a linked delay time register 513 and 523with a user selectable value from 20 μsec (nominally zero delay) up to6.5 seconds, in increments of 100 μsec. Delay times can be entered anddisplayed in milliseconds or in TV fields (NTSC or PAL). It is preferredthat this function be implemented with programmable logic configured inresponse to and operating in conjunction with a microprocessor.

Any input channel and its time value can be routed through the controlrouter 531 to any of the output timers 541 and 551 and each timer cansteer a separate audio synchronizer, as an AD-3100 Audio Synchronizer.The control router is under microcontroller control. It is preferredthat this function be implemented with programmable logic configured inresponse to and operating in conjunction with a microprocessor.Typically, the microprocessor is at least an eight bit microcontrollerwith 32 I/O lines, timers, counters, interrupts, priority levels, and anon-chip RAM. One microcontroller useful in the router 531 describedherein is an Intel 80C32 microcontroller. The Intel 80C32microcontroller is an 8 bit microcontroller with 32 I/O lines, 3timers/counters, 6 interrupts/4 priority less, and 256 bytes of on-chipRAM.

The microprocessor controls a multistate transceiver characterized by abus interface, three state buffers with three state compatible send andreceive directions.

The output timers, 541 and 551, provide TTL level steering pulses to theaudio synchronizer to control the delay of the synchronizer can havedifferent time values and can be turned on and off independently. Also,any timer can be controlled by more than one input channel. Assume thatone switcher effect needs a one frame audio delay and another effectneeds a two frame audio delay. Input #1 (or any other input) can enablea 1 frame delay in Timer #3 (or any other timer) and the associatedaudio synchronizer, as an AD-3100. Any other input can be used to enablea 2 frame delay in the same timer. It is preferred that this function beimplemented with programmable logic configured in response to andoperating in conjunction with a microprocessor.

Program Product

The invention may be implemented, for example, by having the mutualevent detection and synchronization as a software application (as anoperating system element), a dedicated processor, or a dedicatedprocessor with dedicated code. The software executes a sequence ofmachine-readable instructions, which can also be referred to as code.These instructions may reside in various types of signal-bearing media.In this respect, one aspect of the present invention concerns a programproduct, comprising a signal-bearing medium or signal-bearing mediatangibly embodying a program of machine-readable instructions executableby a digital processing apparatus to perform a method for detectingvideo and audio mutual events, determining the delay, and applying asynchronization delay to the audio and video.

This signal-bearing medium may comprise, for example, memory in server.The memory in the server may be non-volatile storage, a data disc, oreven memory on a vendor server for downloading to a processor forinstallation. Alternatively, the instructions may be embodied in asignal-bearing medium such as the optical data storage disc.Alternatively, the instructions may be stored on any of a variety ofmachine-readable data storage mediums or media, which may include, forexample, a “hard drive”, a RAID array, a RAMAC, a magnetic data storagediskette (such as a floppy disk), magnetic tape, digital optical tape,RAM, ROM, EPROM, EEPROM, flash memory, magneto-optical storage, paperpunch cards, or any other suitable signal-bearing media includingtransmission media such as digital and/or analog communications links,which may be electrical, optical, and/or wireless. As an example, themachine-readable instructions may comprise software object code,compiled from a language such as “C++”.

Additionally, the program code may, for example, be compressed,encrypted, or both, and may include executable files, script files andwizards for installation, as in Zip files and cab files. As used hereinthe term machine-readable instructions or code residing in or onsignal-bearing media include all of the above means of delivery.

Other Embodiments

While the foregoing disclosure shows a number of illustrativeembodiments of the invention, it will be apparent to those skilled inthe art that various changes and modifications can be made hereinwithout departing from the scope of the invention as defined by theappended claims. Furthermore, although elements of the invention may bedescribed or claimed in the singular, the plural is contemplated unlesslimitation to the singular is explicitly stated.

1. A method of producing time synchronized multi-media signalscomprising inputting a Tally line for each video input, generating aTimer On/Off signal and a Time Value signal for each Tally, and inresponse to said Time Value and said Tally, providing a delay steeringpulses to an audio synchronizer.
 2. The method of claim 1 furthercomprising inputting a GPI start pulse and a GPI stop pulse for eachtally.
 3. The method of claim 2 further comprising generating a TimerOn/Off signal and a Time Value signal for each set of a GPI Start pulse,a GPI Stop pulse and Tally.
 4. The method of claim 3 further comprising,providing the Timer On/Off signal and a Time Value signals to a router,and routing the signals as delay steering pulses to an audiosynchronizer.
 5. The method of claim 1 comprising selecting a delay timefor each latch.
 6. The method of claim 5 wherein the delay time for eachlatch is user selectable.
 7. The method of claim 1 comprising: a.providing video inputs to a video switcher to provide video output anddelay steering pulses; b. providing audio inputs and the delay steeringinputs to an audio delay; and c. providing input from the audio delay toan audio mixer to provide corrected audio output.
 8. The method of claim1 comprising: a. providing video inputs to a video switcher to providevideo output and delay steering pulses to an audio delay; b. providingaudio inputs to an audio mixer; and c. providing input from the audiomixer to the audio delay to provide corrected audio output.
 9. A systemfor producing time synchronized multi-media signals comprising: a). avideo switcher having internal DVEs for receiving Tally lines for eachvideo input, generating a Timer On/Off signal and a Time Value signalfor each Tally, b). a router for receiving the Timer On/Off signal and aTime Value signals and routing delay signal pulses; and c). an audiosynchronizer receiving the delay signal pulses and outputting audiosignals synchronized to the video output signals.
 10. The system ofclaim 9 further comprising the video switcher having internal DVEs forreceiving GPI Start pulses, GPI Stop pulses and Tally lines for eachvideo input.
 11. The system of claim 9 further comprising a videoswitcher having internal DVEs for generating a Timer On/Off signal and aTime Value signal for each set of GPI Start pulse, GPI Stop pulse andTally.
 12. The system of claim 9 further comprising means for selectinga delay time for each latch.
 13. The system of claim 12 wherein thedelay time is user selectable.
 14. The system of claim 9 comprising: a.a video switcher for receiving video inputs and outputting video outputsand delay steering pulses; b. audio delay means receiving audio inputsand the delay steering inputs; and c. an audio mixer receiving inputsfrom the audio delay, said audio delay outputting corrected audiooutput.
 15. The system of claim 9 comprising: a. a video switcher forreceiving video inputs and outputting video outputs and delay steeringpulses; b. audio mixer means receiving audio inputs and the delaysteering inputs; and c. audio delay means receiving input from the audiomixer means and outputting corrected audio output.
 16. A program productcomprising a storage medium carrying program code for producing timesynchronized multi-media signals by a method comprising inputting aTally line for each video input, generating a Timer On/Off signal and aTime Value signal for Tally, providing the Timer On/Off signal and aTime Value signals to a router, and routing the signals as delaysteering pulses to an audio synchronizer.
 17. The program product ofclaim 16 further comprising program code for producing time synchronizedmulti-media signals by a method comprising inputting a GPI Start pulse,a GPI Stop pulse and a Tally line for each video input.
 18. The programproduct of claim 16 further program code for generating a Timer On/Offsignal and a Time Value signal for each set of GPI Start pulse, GPI Stoppulse and Tally providing the Timer On/Off signal and a Time Valuesignals to a router, and routing the signals as delay steering pulses toan audio synchronizer.
 19. The method of claim 16 comprising selecting adelay time for each latch.
 20. The program product of claim 19 whereinthe delay time is user selectable.
 21. The program product of claim 16wherein the method comprises: a. providing video inputs to a videoswitcher to provide video output and delay steering pulses; b. providingaudio inputs and the delay steering inputs to an audio delay; and c.providing input from the audio delay to an audio mixer to providecorrected audio output.
 22. The program product of claim 16 comprising:a. providing video inputs to a video switcher to provide video outputand delay steering pulses to an audio delay; b. providing audio inputsto an audio mixer; and c. providing input from the audio mixer to theaudio delay to provide corrected audio output.